Method of constructing concrete manholes having sealed joints with pipes connected thereto

ABSTRACT

A method of effecting a joint between a pipe and underground manhole walls or the like utilizes an adapter ring secured and sealed in an aperture of the manhole wall and having an internal diameter accommodating the particular diameter pipe to be sealed with a gasket surrounding the pipe and urged by a gland ring having fasteners cooperating with the adapter ring into fluid pressure sealed relation between the internal diameter of the adapter ring and a radially opposed peripheral surface of the pipe. The construction is such that a workman effecting the pipe joint may work within the safety of the manhole. The adapter rings and manholes have common matching bevelled surfaces and the adapter rings have various internal diameters such that a given manhole may be adapted to various size pipes by selecting the adapter ring having an internal diameter accommodating the particular pipe selected, thereby reducing manhole inventory.

United States Patent Washabaugh et al.

[ Jan. 29, 1974 Primary Examiner-Richard J. Herbst AssistantExaminer-Donald C. Reiley, Ill

'Attorney, Agent, or Firm-Burton and Parker [76] Inventors: William E.Washabaugh, 5354 Hilltop Dr.; Edward Peter Washabaugh, Jr., 1701 Mosher,[57] ABSTRACT both of Bay city Mlch' 48706 A method of effecting a jointbetween a pipe and un- [22] Filed: June 16, 1971 derground manhole wallsor the like utilizes an adapter ring secured and sealed in an apertureof the [21] Appl' 153572 manhole wall and having an internal diameteraccommodating the particular diameter pipe to be sealed [52] U. S. I l6H2, 29/ 157 l 22/5 27 1, with a gasket surrounding the pipe and urgedby a 52/21,52/742, 52/746, 137/363, gland ring having fastenerscooperating with the 277/101, 285/194, 285/230, 156/245, 61/11, adapterring into fluid pressure sealed relation be- 61/ 13, 61/16 tween theinternal diameter of the adapter ring and a [51] Int. Cl E04b 1/16radially opposed peripheral surface of the pipe. The [5 8] Field ofSearch 52/20, 21, 741, 746, 742; construction is such that a workmaneffecting the pipe 277/101; 29/157 R, 527.1; 137/363; 61/2, joint maywork within the safety of the manhole. The 11, l3, 16; 156/245; 285/194, 230 adapter rings and manholes have common matching bevelledsurfaces and the adapter rings have various [56] References Citedinternal diameters such that a given manhole may be UN D STA P S adaptedto various size pipes by selecting the adapter I 3,348,850 10/1967Scales 277 101 ring.ha"ing.an internal diameter acclmmodating l3,543,457 12/1970 Budlong 52/20 x Pammlar We selected thereby educmgmanhde 3,654,952 4/1972 Howe 137/363 y- 2,166,632 7/1939 Hardesty etal.. 52/20 X 3,212,519 10/1965 Pascher 52/21 x- 7 Clam, 7 D'awmg////////////////7 76 c 0 a o o o I o s- 24 O I 7J- o I z METHOD OFCONSTRUCTING CONCRETE MANHOLES HAVING SEALED JOINTS WITH PIPES CONNECTEDTHERETO FIELD OF THE INVENTION This disclosure relates to joints betweenconcrete manholes or the like and pipes to be projected through themanhole wall and sealed therein. The disclosure also relates to methodsof constructing such joints and methods of constructing manholes tofacilitate effectuating such pipe joints.

BACKGROUND OF THE DISCLOSURE for many years problems have beenencountered in effecting long-lasting fluid-tight joints betweenconcrete manholes and the like and pipes to be connected to themanholes. These problems have arisen because of a variety of factorswhich include but are not limited to the following: wide variations inthe configurations and actual external diameters of nominallycylindrical equal diameter pipes to be sealed; the d'ifficulty inaccurately forming and sizing manhole pipe-receiving apertures; thetendency of manholes or the pipes joined thereto to shift or settle inthe earth thereby imposing strains in the joints and relative movementbetween the manhole and pipe at the joint tending to destroy thefluid-tight seal; the difficulty in accurately aligning the pipe laid inthe trench and the aperture in the manhole wall; and the dangers ofcave-in on the workmen in the pipe trench while effecting a seal betweenthe pipe and the manhole. The problems arising from variations inexternal configuration and pipe diameters of nominally equal pipe andaccuracy of alignment of pipe with the manhole aperture have beentreated and solutions suggested in U. S. Pat. No. 3,348,850, wherein themanhole wall is provided with a pipe-receiving aperture having anexternal bevelled entrance and a gland ring and an O-ring gasket aretelescoped over the pipe before it is projected through the aperture andthe gasket urged axially against the external bevelled aperture entranceby threaded fasteners cooperating with the gland ring and received inthreaded inserts in the exterior surface of the manhole wall around theaperture. While the teachings of US. Pat. No. 3,348,850 have improvedthe effectiveness of the pipe joint, substantial problems are inherentwith the use of such teachings including the following: the workman musteffect the seal at the time the pipe is laid in the trench because boththe gland ring and resilient O-ring seal must be inserted over the pipebefore the same is projected through the manhole wall, and thereafterthe workman must tighten the threaded fasteners from outside themanhole, and during all such he is subjected to the danger of trenchcave-in; upon filling the pipe trench, should a leak subsequently occurin the joint, the earth must be removed to gain access to the joint totighten it; the pipe manufacturer must maintain a substantial inventoryof manholes which differ from one another only in the size of thepipe-receiving apertures to accommodate the varying external diameterpipes which may be called for; following the teaching of such patentthere is a limitation upon the maximum external diameter pipe that maybe sealed in a given diameter manhole, for example in a 48-inch diametermanhole an 18-inch external diameter pipe is the maximum that can besafely used and insure an effective seal, while it would be desirable toallow an effective seal up to a 24-inch external diameter pipe in a48-inch diameter manhole; the configuration of the aperture in themanhole wall required by the teaching of such patent is difficult toinsure during casting of the manhole in the absence of special machinerynot possessed by many manhole manufacturers and even if possessedrequires special precautions to insure that the aperture is properly andfully formed.

SUMMARY OF THE DISCLOSURE We have overcome the foregoing objections tothe teachings of US. Pat. No. 3,348,850 and have also provided a numberof other positive advantages in the method of effecting a pipe joint andconstructing the manholes associated therewith as taught in thisapplication. In accordance with our disclosure the manholes are formedwith a bevelled aperture opening outwardly through the exterior of themanhole wall and into this aperture is secured and sealed an adapterring having an internal bevel surface which faces in a direction to openinto the enclosure of the manhole such that a workman effecting thejoint can accomplish the same working within the safety afforded by themanhole itself, it only being necessary to project the pipe during thepipe-laying operation through the internal diameter of the adapter ringand thereafter the joint is completed from within the manhole. As thepipelaying operation in this regard may be carried out from the surfaceof the ground, the necessity of sending a workman into the trench at theexterior of the manhole may in some instances be avoided.

As our disclosure provides for effecting the fluidtight joint betweenthe manhole wall and the pipe from within the manhole, should the jointfor any reason begin to leak, it can be serviced from within the manholewithout excavating to the pipe outside the manhole. Inventory ofmanholes may be drastically reduced utilizing the adapter ring conceptbecause manholes may be formed with standard size bevelled aperturestherein and the adapter rings may have a standard external bevelleddiameter and vary only in the internal bevelled diameter. As the cost ofmanufacture and inventory of manholes is many times greater than thecost of manufacturing an inventory of adapter rings, a manholemanufacturer may, utilizing our invention, maintain only such number ofa given size manhole as may be reasonably demanded, and then maintain aninventory of adapter rings to accommodate anticipated demand for thevarious diameter pipes. When a customer calls for a given size manholewith a given size pipe, the manhole manufacturer need only select fromhis manhole inventory the proper diameter manholes, and from his adapterring inventory those rings having a suitable internal bevelled diameter,and then insert the adapter rings in the selected manholes and secureand seal them therein to satisfy the customers requirements.

manufacture and substantially reduces the uncertainty in the sufficiencyof the aperture configuration to afford an effective seal with the pipe.

As the gland ring is connected to the adapter ring, manufacturingproblems in assuring satisfactory embedding of fastener-receivinginserts in the manhole wall are overcome.

Other objects, advantages and meritorious features will be apparent fromthe following description, claims and drawings.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a cross-sectional elevationthrough a manhole embodying our improved pipe joint;

FIG. 2 is a schematic cross-sectional elevation through apparatus formanufacturing concrete manholes which will accommodate our improvedjoint and illustrates method aspects of our invention;

FIG. 3 is a cross-sectional view taken on the 3--3 of FIG. 2;

FIG. 4 is a schematic cross-sectional elevation through a packer headfor making concrete manholes which will accommodate our improved jointand illustrates method aspects of our invention;

FIG. 5 is a fragmentary view on the inside of a manhole showing the pipejoint;

FIG. 6 is a cross-sectional view taken on the line 66 of FIG. 5 with aportion of the gland ring omitted for clarity; and

FIG. 7 is a fragmentary cross-sectional view through one side of theadapter ring showing the relationship of the same to the manhole wall,the pipe, sealing and gland rings.

DESCRIPTION OF PREFERRED EMBODIMENTS A typical manhole installationembodying our improved pipe joint is shown in FIG. 1 as including abottom section 10 having superimposed connected sections 12 and 14opening upwardly through a paved surface such as a roadway or the like16 through suitable upper sections 18 and 20. The manhole sections 10,12 and 14 are formed of concrete. Access may be gained to the interiorthereof through the upper section 20 in the usual fashion. The sections10, 12 and 14 are connected by nested bell and spigot ends inconventional fashion. The bottom 22 of the manhole is shown in FIG. 1 asbeing integral with the encircling side wall of the lower section 10but, as is well understood in the art, the bottom may be a separatepiece which is suitably interfitted with the lower edge of section 10and sealed and secured thereto in a conventional manner.

line

In a typical manhole installation one or more pipe lines are connectedto the manhole, generally to the section 10. It is conventional practiceto extend the pipe through the wall of the section and seal it therein.The invention herein disclosed is concerned with methods and structuresfor effecting such pipe joints and is applicable to undergroundconnections between pipes and underground chambers and the term manholeas used herein is intended to generically cover any underground chamber.

The construction and arrangement of a pipe joint embodying the inventionis shown particularly in FIGS. 5-7. The generally circular manhole wall24 is provided with a circular aperture 25 extending therethrough. Theaperture is configured to have a bevelled exterior entrance provided bya bevelled wall 26 extending from the exterior surface 28 to theinterior surface 30 of the manhole wall 24. The included angle of thisbevelled surface 26 as shown in FIG. 6 is approximately 30. Secured innested and sealed relation within the aperture 25 is an annular adapterring 32 in the form of a truncated cone or frustum. The ring has anouter peripheral bevelled surface 34 which matches the bevelled entrance26 with the external diameter of the adapter ring being such that itwill nest down within the aperture substantially as shown in FIGS. 6 and7.

The depth of this nested arrangement is preferably such that theexterior end face 36 lies along its vertical diameter within theexterior peripheral surface 28 of the manhole wall indicated 38 in FIG.6.

The internal diameter or axial opening through the adapter ring includesa bevelled entrance or sealing portion 40 which opens through that endface 42 of the ring facing the interior of the manhole. The bevelledportion 40 terminates at its inner end at a bevelled entrance portion 44which extends through the exterior face 36 of the adapter ring. It willbe noted that the bevels 34 and 40 of the adapter ring are on oppositeangles.

Embedded in the ring at least at three, and in the drawings at four,equidistantly spaced points are internally threaded inserts 46 eachadapted to receive a threaded fastener or bolt 48 for securing inadjusted axial positions a rigid gland ring 50. The gland ring includesan axially extending portion 52 and a radial flange portion 54 which isprovided at equidistantly spaced locations with bifurcated ears 56through which are received the bolts with the heads thereof overlyingthe ears. A rubber O-ring or the like 58 encircles the projecting end ofthe pipe P and is urged by the end face 59 of the axially extendingportion 52 of the gland ring against the bevelled surface 40 of theadapter ring to cause the O-ring to be squeezed radially against anopposed circumferential surface portion of the pipe P to effect a sealbetween the adapter ring and the pipe.

The O-ring when axially compressed is deformed substantially to theconfiguration shown in FIG. 7 and serves to support the projecting endof the pipe P spaced inwardly from the walls 40 and 44 of the adapterring and permits the seal to be effected despite angular displacement ofthe pipe as to the position P shown in FIG. 6 and otherwise accommodatesfor misalignment between the pipe and the aperture in the adapter ring.

The adapter ring is disclosed as being formed of concrete. It may beeither wet or dry cast. It is internally reinforced by reinforcing meanswhich are spaced from the external surfaces of the adapter ring. Suchreinforcing means may comprise one or more steel reinforcing rings 60and 62 held in aligned spaced apart relation by suitable spacing wires64 disposed at circumaxially spaced locations around the reinforcingrings. The rings 60 and 62 together with the spacer 64 may compriseconventional strips of concrete pipe caging which has been bent intocircular form with the ends secured together in any suitable fashion asby welding.

In lieu of forming the adapter ring of concrete, the

same may be formed of a high durometer rubber or suitable plasticmaterial having the requisite strength and deterioration resistantproperties adapting it for the intended use.

Preferably, however, the adapter ring is formed of concrete as such maybe economically manufactured. The inserts 46 are cast in the adapterring at the time of its manufacture and are shaped in the general formof a truncated cone having a flange at the base with the entireconfiguration of the insert resisting tendency to pull out upontightening of the bolt.

The adapter ring is, in the preferred form of the invention, secured inthe aperture of the manhole wall 24 by adhesive bonding such as an epoxyor urethane adhesive which is spread on either or both of the surfaces26 and'34 just prior to insertion of the adapter ring into the wallaperture. A number of such adhesives are commercially available whichwill prove satisfactory in both strength and long enduring qualities andwhich will effect a fluid-tight seal at the interface between thesurfaces 26 and 34.

In practice, the adapter ring is preferably installed in the manholewall by the manhole manufacturer such that the manhole is shipped to theexcavation site with the adapter ring in place. Following placement ofthe manhole in the ground, the pipe to be connected is laid in a trenchoutside the manhole and an end thereof projected through the adapterring as shown in FIG. 6. The workman, operating within the manhole, thentelescopes the O-ring 58 over the projecting end of the pipe, followedby the gland ring 50 and urges the O- ring and gland ring axially towardthe adapter ring. The bolts 48 are inserted through the bifurcated ears56 on the gland ring and tightened to axially squeeze the O- ringagainst the bevelled surface to effect the seal between the adapter ringand the pipe P. The entire operation by the workman in assembling thejoint and effecting a fluid-tight seal may be accomplished within themanhole. Upon backfilling the pipe trench outside the manhole, theweight of the earth will press against the exterior end face 36 of theadapter ring urging it into the manhole wall aperture 25. Should itsubsequently be discovered that a leak has occurred at the joint betweenthe pipe and the adapter ring, a workman can descend into the manholeand tighten the bolts 48, or alternatively replace the entire O-ringshould such be necessary, without disturbing the earth outside themanhole.

By making the pipe joint utilizing the adapter ring disclosed herein itis possible for a given diameter manhole to accommodate a substantiallylarger pipe than has been. possible when following the teaching of U.S.Pat. No. 3,348,850. The reason for this will become apparent from aconsideration of FIGS. 6 and 7 'wherein it will be noted that as thediameter of the pipe is increased, a point is reached at which acontinuous planarsealing surface for accommodating the O-ring will ceaseto exist-if the O-ring is pressed directly against the exterior of themanhole wall as contemplated by such patent. However, by utilizing theadapter ring, the bevelled surface 40 against which the O-ring seals canbe made to a greater diameter than heretofore possible because suchsurface is essentially independent of manhole diameter as the adapterring itself provides the bevelled sealing surface against which theO-ring seats, and not the surface of the manhole wall. It hasbeen foundthat, for example, we can provide an effective joint where the pipediameter is 24-inches and that of the manhole 48-inches.

A substantial economy in the manufacture of manholes may be effectedutilizing the disclosure herein disclosed. According to the invention,manholes of a given diameter may be provided with uniform size apertures25 and the adapter rings to be received therein have correspondinglymatching external diameters 34. To accommodate the various size pipeswhich it may be desired to utilize with the manholes, the adapter ringsmay be provided with internal apertures of correspondingly varyingdiameters to accommodate the different size pipes. As a consequenceinventory of manholes may be drastically reduced as any manhole ininventory of a given size can, by the insertion of the proper adapterring, accommodate any given diameter pipe that may be expected to beused with such manhole. As the cost of manufacture and inventory ofadapter rings is substantially less than that of manholes, the manholemanufacturer may maintain a much larger inventory of adapter rings and asmaller inventory of manholes with his total investment substantiallyless than was heretofore possible while taking advantage of the O-ringand gland type joint.

In the manufacture of manholes for effecting pipe joints according tothe teachings hereinbefore described, and considering conventionalpractices in manufacturing manholes, there is shown in FIGS. 2-4 methodsof manhole manufacture according to the disclosure. ln FIG. 2 themanhole section is manufactured to provide integral side wall 24 andbottom wall 22. The manhole section is cast upside down on a supportshown schematically at 70. An outer strippable form 72 closed at the topby a top form 74 defines the exterior configuration of the manholesection. The internal configuration of the manhole section is defined byan inner form 75 supported on the support 70. To form the aperture 25 inthe manhole wall a frusto-conical plug 76 is disposed between the innerand outer forms with its base 78 against the inner surface of the outerform 72 and its top 80 against the inner form 75. The base 74 and top 80are formed on a curve matching that of the inner and outer wall surfacesof the manhole wall and the plug is secured to the outer form 72 as by athreaded fastener in the form of a bolt 82 which is threaded into thebase 78 of the plug.

The outer form may be separable in the conventional manner to allow itseasy removal from the manhole. The inner form 75 may be formed forslight inward collapse or disassembly to similarly allow easy removalfrom within the formed manhole. However, until the manhole concrete hascured, it is the practice to maintain the manhole in its invertedposition as shown in FIG. 2 whereby access to its interior cannot begained until the manhole is reverted to its normal position with thebottom wall 22 disposed lowermost and with the section open at the top.

Before casting the manhole according to the method disclosed in FIGS. 2and 3, the frusto-conical plug 76 is attached to the outer form. Withthe top form section 74 removed, concrete is packed between the innerand outer forms and about the conical plug and thereafter the top 74 maybe added, or if desired omitted following smoothing of the exterior ofthe bottom wall 22. When the concrete will hold its shape without aid ofthe outer form 72, the latter may be stripped from the manhole afterremoval of the bolt 82. Following stripping, the frusto-conical plug maybe removed and final curing of the concrete effected. It will be notedthat the plug may be removed from the manhole wall without the need ofgaining access to the interior of the manhole section, as is the casewith the method of US. Pat. No. 3,348,850, and this allows earlier reuseof the frusto-conical plug 86 in the manufacture of succeeding manholesthan if it were necessary to wait until the manhole could be inverted togain access to its interior. Such inversion is in practice delayed untilthe concrete is substantially completely cured so as to avoid any dangerof disturbing proper setting of the concrete in its properly compactedor formed condition.

In FIG. 4 the method of making a manhole section on a packer headincorporating the invention is disclosed. The packer head is ofconventional construction and is schematically illustrated. The packerhead method of pipe casting utilizes a base ring 86 supported by anouter strippable form 90 which is separable to allow its subsequentremoval from the manhole section. Form 90 is supported on the table 103and extends upwardly to a spigot-forming ring 92. The packer head 94 iscarried by a vertically reciprocable and rotatable shaft 96. Vibrators Vare mounted on the vibrator ring 88 to effect radial vibration of theconcrete during the bell packing operation.

A frusto-conical plug 98 corresponding to that heretofore described issecured with its base 100 against the inner surface of the outer form 90with the plug being held to the outer form by a threaded fastener or thelike 102 which is threaded into the base 100. The top 104 of the plug isconcave and lies flush with what will be the inner surface of themanhole section. As is understood in the art, with the packer head 94disposed adjacent the base ring 86, concrete is introduced above thepacker head and as the same revolves the concrete is swept radiallyoutwardly against the outer form and downwardly against the base ringand as the packer head continues to rotate and is elevated and concreteadded, the manhole section is formed until the upper ring is reached.During such vertical and rotational movements of the packer head therollers R serve to compact the concrete against the outer form and aboutthe frusto-conical plug 98. By virtue of the frusto-conical shape of theplug 98 the concrete is suitably packed thereabout despite the fact thatthe packer head is only unidirectionally rotated. Upon completion of themanhole section the packer head is withdrawn out of the top of themanhole section and the thus formed manhole and the base and upper ringsmoved as a unit to a curing site where the outer form is strippedfollowing removal of the threaded fastener 102. The frusto-conical plugmay be temporarily left in the green concrete until it has setsufficiently so that the plug may be removed without sagging of theconcrete. In practice the plug may be removed before full curing of theconcrete to allow reuse of the plug in subsequent manufacture ofsucceeding manhole sections while the section from which the plug isremoved continues its curing.

It will be apparent from the above description that it would be possibleto utilize the same adapter rings in various diameter manhole sectionssimply by forming the proper diameter aperture 25 having the bevelledentrance 26 corresponding to that of the adapter rings. In this fashioneconomies may be effected in inventory of adapter rings, as an adapterring for say a 16-inch diameter pipe may be utilized in manhole sectionsof 48-inch diameter, 72linch diameter, etc.

What is claimed is:

1. In the method of constructing concrete manholes or the like toprovide a sealing surface for effectuating a sealed pipe joint with themanhole wall wherein the manholes are formed within a strippable formthe improvement comprising the steps of:

securing to the inner surface of the form a frustoconical plug with itsbase against the form and its top projecting to the inner surface wallline of the manhole to be formed,

forming the concrete manhole within the form,

releasing the plug from the form and stripping the form from the manholewall, removing the plug from the formed manhole wall by extracting itfrom the exterior of the manhole,

forming an adapter ring having a bevelled exterior diameter matching thebevel aperture formed by the plug in the manhole wall and having aninternal bevelled diameter providing a sealing surface sized to closelyembrace a pipe to be connected to the manhole, and

inserting and sealing the adapter ring in the manhole aperture formed bythe plug.

2. The invention defined in claim 1 wherein the adapter ring is insertedand sealed in the manhole aperture following curing of the manhole wall.

3. The invention defined in claim 2 wherein the adapter ring is sealedand retained in the manhole aperture by adhesively securing it therein.

4. The invention defined in claim 1 wherein the adapter ring is formedof concrete.

5. The method of constructing scaled joints between pipes andunderground manhole walls or the like comprising:

forming manholes with uniform diameter apertures through the wallsthereof for receiving therein adapter rings,

forming adapter rings having in common an external diameter andconfiguration to be secured and sealed in the manhole wall apertures andhaving selected internal diameters to accommodate selected pipediameters,

during formation of the adapter rings providing an internal bevelledsurface extending axially and radially outwardly to face interiorly of amanhole when the ring is secured and sealed in the aperture thereof,

securing and sealing in the manhole apertures the formed adapter ringshaving internal diameters adapted for sealing with the diameter of pipeto be joined to the manhole,

installing the manholes in the ground,

laying pipe in a trench outside the manhole and projecting an end of thepipe through the adapter ring,

positioning a resilient gasket about the end of the pipe projectinginteriorly of the manhole, and

urging the gasket from within the manhole against the inwardly facingbevelled surface of the adapter ring to squeeze the gasket against anopposed surface of the pipe to seal the pipe in the manhole wall.

6. In the method of constructing concrete manholes or the like tofacilitate effectuating a sealed pipe joint between the manhole wall andvarious diameter pipes wherein the manholes are formed within astrippable form, the improvement comprising the steps of:

securing to the inner surface of the form a frustoconical plug with oneend against the form and its other end projecting to the inner surfacewall line of the manhole to be formed,

forming the concrete manhole within the form and about the plug, I

releasing the plug from the form and stripping the form from the manholewall,

removing the plug from the formed manhole wall,

forming an adapter ring having a bevelled exterior diameter matching thebevel aperture formed by the plug in the manhole wall and having aninternal diameter sized to closely embrace the diameter pipe to beconnected to the manhole,

and inserting and sealing the adapter ring in the manhole apertureformed by the plug.

* 7. The method of constructing sealed joints between pipes andunderground manhole walls or the like comprising:

forming manholes with uniform diameter apertures.

through the walls thereof for receiving therein and from within themanhole effecting an annular seal between the pipe and the adapter ringthrough the annular space between the internal bevelled surface of thering and the confronting surface of the pipe.

1. In the method of constructing concrete manholes or the like toprovide a sealing surface for effectuating a sealed pipe joint with themanhole wall wherein the manholes are formed within a strippable formthe improvement comprising the steps of: securing to the inner surfaceof the form a frusto-conical plug with its base against the form and itstop projecting to the inner surface wall line of the manhole to beformed, forming the concrete manhole within the form, releasing the plugfrom the form and stripping the form from the manhole wall, removing theplug from the formed manhole wall by extracting it from the exterior ofthe manhole, forming an adapter ring having a bevelled exterior diametermatching the bevel aperture formed by the plug in the manhole wall andhaving an internal bevelled diameter providing a sealing surface sizedto closely embrace a pipe to be connected to the manhole, and insertingand sealing the adapter ring in the manhole aperture formed by the plug.2. The invention defined in claim 1 wherein the adapter ring is insertedand sealed in the manhole aperture following curing of the manhole wall.3. The invention defined in claim 2 wherein the adapter ring is sealedand retained in the manhole aperture by adhesively securing it therein.4. The invention defined in claim 1 wherein the adapter ring is formedof concrete.
 5. The method of constructing sealed joints between pipesand underground manhole walls or the like comprising: forming manholeswith uniform diameter apertures through the walls thereof for receivingtherein adapter rings, forming adapter rings having in common anexternal diameter and configuration to be secured and sealed in themanhole wall apertures and having selected internal diameters toaccommodate selected pipe diameters, during formation of the adapterrings providing an internal bevelled surface extending axially andradially outwardly to face interiorly of a manhole when the ring issecured and sealed in the aperture thereof, securing and sealing in themanhole apertures the formed adapter rings having internal diametersadapted for sealing with the diameter of pipe to be joined to themanhole, installing the manholes in the ground, laying pipe in a trenchoutside the manhole and projecting an end of the pipe through theadapter ring, positioning a resilient gasket about the end of thE pipeprojecting interiorly of the manhole, and urging the gasket from withinthe manhole against the inwardly facing bevelled surface of the adapterring to squeeze the gasket against an opposed surface of the pipe toseal the pipe in the manhole wall.
 6. In the method of constructingconcrete manholes or the like to facilitate effectuating a sealed pipejoint between the manhole wall and various diameter pipes wherein themanholes are formed within a strippable form, the improvement comprisingthe steps of: securing to the inner surface of the form a frusto-conicalplug with one end against the form and its other end projecting to theinner surface wall line of the manhole to be formed, forming theconcrete manhole within the form and about the plug, releasing the plugfrom the form and stripping the form from the manhole wall, removing theplug from the formed manhole wall, forming an adapter ring having abevelled exterior diameter matching the bevel aperture formed by theplug in the manhole wall and having an internal diameter sized toclosely embrace the diameter pipe to be connected to the manhole, andinserting and sealing the adapter ring in the manhole aperture formed bythe plug.
 7. The method of constructing sealed joints between pipes andunderground manhole walls or the like comprising: forming manholes withuniform diameter apertures through the walls thereof for receivingtherein adapter rings, forming adapter rings having in common anexternal diameter and configuration to be secured and sealed in themanhole wall apertures and having selected internal diameters toaccommodate selected pipe diameters, securing and sealing in the manholeapertures the formed adapter rings having internal diameters adapted forsealing with the diameter of pipe to be joined to the manhole,installing the manholes in the ground, laying pipe in a trench outsidethe manhole and projecting an end of the pipe through the adapter ring,and from within the manhole effecting an annular seal between the pipeand the adapter ring through the annular space between the internalbevelled surface of the ring and the confronting surface of the pipe.